Write your own version of strncpy(s1,s2,n) function

Introduction

strncpy(s1,s2,n) function copies exactly n characters from s2 to s1, truncating s2 or padding it with extra null characters as necessary.

Demo Code

#include <stdio.h>  
#include <string.h>  

#define LEN 80  /*w  w  w  . j  av a 2s  .  c  om*/

bool is_within(const char * str, char c);
char * s_gets(char * st, int n);

int main(void) {
   char input[LEN];
   char ch;
   int found;;

   printf("Enter a string: ");
   while (s_gets(input, LEN) && input[0] != '\0') {
      printf("Enter a character: ");
      ch = getchar();
      while (getchar() != '\n')
         continue;
      found = is_within(input, ch);
      if (found == 0)
         printf("%c not found in string.\n", ch);
      else
         printf("%c found in string %s\n", ch, input);
      printf("Next string: ");
   }
   puts("Done.\n");

   return 0;
}

bool is_within(const char * str, char ch) {
   while (*str != ch && *str != '\0')
      str++;
   return *str;   /* = 0 if \0 reached, non-zero otherwise */
}

char * s_gets(char * st, int n) {
   char * ret_val;
   char * find;

   ret_val = fgets(st, n, stdin);
   if (ret_val) {
      find = strchr(st, '\n');   // look for newline  
      if (find)                  // if the address is not NULL,  
         *find = '\0';          // place a null character there  
      else
         while (getchar() != '\n')
            continue;
   }
   return ret_val;
}

Write your own version of strncpy(s1,s2,n) function - C String

Introduction

Demo Code

Result

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